Temperature stabilization bodies are primarily used to provide a temperature which is as constant and uniform as possible within a predetermined space, so that, on a surface or zone in the space, the temperature transfer to elements located within that space will be constant and uniform. Temperature stabilization bodies are used usually in those installations where temperature gradients should be as small as possible. Temperature stabilization bodies, for example, are utilized in carefully temperature controlled processes, such as processes involving melting and pulling of single crystals, for example for semiconductor use, highest quality and purity glasses and the like, quartz crystals, and for similar applications. The temperature stabilization bodies may be, for example, in form of a tube, an external boat or mortar, or a jacket applied over or around all or at least on a portion of a pulling boat or mortar. Temperature stabilization bodies also find use in thermal analysis apparatus, in form of furnace liners or blocks, for heat treatment during sintering and/or high temperature and pressure treatment; they may be constructed in form of a lining for furnaces, or furnace inserts.
When used in low-temperature ranges--considering the application for which temperature stabilization bodies are usually used, that is temperature ranges of less than 1000.degree. C.; it is customary to utilize temperature stabilization bodies made of metal, which have good heat transfer charcteristics, such as copper, silver, or aluminum. Such temperature stabilization bodies, in which heat is conducted readily throughout the body so that the overall temperature of the body shows but little change between respective zones thereof, have the disadvantage that they have a low melting temperature and low recrystallization temperature, already at low temperatures--wherein "low" is intended to mean temperatures of less than 1000.degree. C. Such metallic temperature stabilization bodies, usually in the form of essentially solid sheets, tubes or blocks, have an additional disadvantage: They tend to creep, that is, they tend to deform due to their inherent weight. Metal temperature stabilization bodies cannot be used for higher temperatures, in which "higher" is intended to convey a temperature range in excess of 1000.degree. C., and, typically, substantially in excess thereof.
It has been proposed to use temperature stabilization bodies made of beryllium oxide. In actual practice, beryllium oxide cannot be used since beryllium oxide is highly toxic and, thus, handling of beryllium oxide causes difficulty and preferably should be avoided. Additionally, beryllium oxide, although having excellent heat conductivity at low temperatures, loses this excellent heat conductivity as the temperatures increase and rise into the high-temperature levels, which is frequently required.
It has already been proposed to obtain bodies of any desired shape made by sintering of powder mixture containing aluminum nitride, at least one of the oxides of calcium, barium and strontium and carbon--see U.S. Pat. No. 4,435,513 Komeya et al. Bodies of comparatively high density and good heat conductivity up to about 71 W/m.degree.K. could be obtained thereby. To facilitate sintering of aluminum nitride, it has been proposed to add oxides of the rare-earth metals, for example yttrium oxide or lanthanum oxide, calcium oxide, barium oxide and strontium oxide.